Yù bàng xiāng zhēng, yú wēng dé lì
Translation: A grapple between a snipe and a clamp benefits the fisherman.
Meaning: A dispute between two parties may benefit a third party; two dogs strive for one bone, and a third runs away with it.
During the Warring States period (476 BCE— 221 BCE), the State of Zhao was planning an attack against the State of Yan. A famous lobbyist named Su Dai went to King Huiwen of Zhao to dissuade him from taking action. Instead of cutting to the chase, Su Dai told the king a story, which was recorded in the renowned ancient Chinese historical work titled Zhanguo ce (Strategies of the Warring States) compiled between the third and the first centuries BCE.